1. Field of the Invention
The present invention relates to physical exercise apparatus for use in developing human muscles.
2. Description of the Prior Art
Exercise equipment used to develop human muscles is well known. Among the most widely used of such equipment are machines using weights suspended by cables with the cables passing over one or more pulleys. An exercise handle connected to the free end of the cable provides a means by which a trainee may raise and lower the suspended weights and thus perform a number of prescribed exercises.
However, most prior art exercise machines of this type are equipped with fixed pulleys and are thus capable of providing uniform resistance--and muscle loading--only in linear exercise movements. When rotary exercises are performed on such devices a mechanical advantage is gained over the machine, in certain ranges of exercise movements, with a resulting undesireable decrease in the resistance loads. In all efficient exercise devices, the resistance curve provided should closely match the strength curve of the muscle being trained. However, in regard to rotary movements performed on standard cable, weight stack, fixed pulley devices, this effect cannot be uniformly provided.
Further, the prior exercise devices which utilize weights and fixed pulleys are generally deficient in that they do not provide the means by which the angle of pull is continuously varied throughout exercise movements requiring this effect. Thus the correct angle between the exercise cable and exercising limb is maintained only momentarily in the full range of an exercise movement. Therefore with prior cable training equipment, maximum muscle stimulation is not maintained throughout the full range of an exercise movement.
U.S. Pat. No. 4,154,441 discloses a device for varying the angle of the exercise handle as pulled during utilization of the exercise device. However, the device disclosed has a number of drawbacks. First, several different devices are required to adequately exercise all of the various muscle groups of the human body. Second, several variations on the device disclosed in that patent must be built to oversized dimensions in order to function properly, and thus are difficult to locate in rooms of average dimensions. Third, the device disclosed in this patent tends to unreasonably distort the resistance curve provided by the associated weight stack or other such resistance means. In many exercises performed with the cable/pulley configuration described in this patent, the uniform resistance load provided by lifting a weight vertically, is actually increased up to 60% from the beginning to end range of the exercise movement.